Susceptibility of Streptococcus pneumoniae isolated from the respiratory tract of hospitalized children with respiratory tract infections.

The most frequent nasopharyngeal carriers of Streptococcus pneumoniae are young children. Frequent use of antimicrobial therapy in children facilitates the selection of penicillin-resistant strains in this population. These strains, especially if highly resistant, may cause serious therapeutic problems. Aim of the study was to monitor penicillin- and multidrug-resistant S. pneumoniae strains in hospitalized children with respiratory tract infections. Hospitalized children up to five years were examined for S. pneumoniae presence in their upper respiratory tract. Susceptibility to penicillin, erythromycin, trimethoprim/sulfamethoxazole, tetracycline, and chloramphenicol was determined by the disk-diffusion method. The minimal inhibitory concentrations (MIC) of penicillin, erythromycin and trimethoprim/sulfamethoxazole were measured by the E-test. S. pneumoniae strain was isolated from 60 (34.7%) out of 173 microbiologically examined children; 2 different strains were isolated in 9 cases. Nine strains (13.0%) were penicillin resistant with MICs ranging from 1.5 to 8 mg/L, and 17 strains (24.6%) had intermediate susceptibility. Seventeen (24.6%) strains were erythromycin resistant (MIC > or = 1 mg/L). Eighteen strains (26.1%) were resistant and 7 strains (10.1%) were intermediately susceptible to trimethoprim/sulfamethoxazole. Ten strains (14.5%) were not susceptible to tetracycline, and 11 (15.9%) to chloramphenicol. Non-susceptibility (resistance or intermediate susceptibility) to the tested antimicrobials was more prevalent in penicillin-nonsusceptible strains. The current level of S. pneumoniae resistant to antimicrobial drugs in children with respiratory tract infections in the hospital department monitored in our study do not cause problems in the choice of antibacterial therapy. Penicillins still can remain the drug of choice in cases when typical bacterial causing agents of respiratory tract infections are suspected. (Tab. 3, Fig. 2, Ref. 31.)